On a recent project that needed to keep data in sqlite, I experimented with an implementation of ActiveRecord and also sqlitepersistentobjects. I had passed up a few others that were too complicated or licensed under something like the GPL that prevented commercial work. While the ActiveRecord author has to get an award for the quickest… →
SQLite is a small SQL database engine and it makes a good fit for iPhone apps. You can create a SQLite database and its tables using Base app: http://menial.co.uk/software/base/. Base is a lightweight Mac OS X application.